1. Field of the Invention
The preset invention relates to an arrangement structure for an umbilical member arranged on an industrial robot.
2. Description of the Related Art
In an industrial robot, a work tool, such as a hand or a welding torch, is used while attached to a front end of a wrist of the robot or close to the wrist. In many cases, it is necessary to supply electricity, an electrical signal, air, assist gas, or a welding wire to the work tool. In order to transmit the electricity, etc., to the work tool, an umbilical member constituted by a wire and/or a tube is used. In the conventional arrangement structure for the umbilical member, before reaching a forearm of the robot, the umbilical member is bundled with a servo control cable for driving and controlling a servomotor of each axis of the robot, and is arranged on a robot arm (or an upper arm). Then, from a basal end of the forearm, the umbilical member extends through a hollow portion of a speed reducer having a hollow structure provided at the basal end, and is withdrawn toward outside from an opening formed on a lateral side of the forearm the robot near the front end thereof. Further, the umbilical member is held by a proper holding means near the opening, and is connected to the work tool.
For example, Japanese Unexamined Patent Publication (Kokai) No. 2006-051581 describes that (first and second) openings are formed on a front part (or a first wrist element) and a rear part (or a base part) of a forearm, and the openings are communicated through an inner part of the forearm and a hollow part of a speed reducer.
Japanese Unexamined Patent Publication (Kokai) No. 2005-342860 describes that, when a adsorption-type hand is used, the inside of a conduit connected to the hand is sucked by air, in order to prevent dust, etc., generated by friction of an umbilical member within the conduit, from flowing outside of the conduit.
Further, Japanese Unexamined Patent Publication (Kokai) No. 2009-028875 discloses a configuration wherein a conduit, through which an umbilical member is inserted, is supported by a second wrist element in a cantilever manner, so that an inappropriate force is not applied to the conduit or the umbilical member in the conduit. Further, this document discloses means for rotatably holding the conduit and means for fully fixing the conduit, as examples of holding the conduit.
In the umbilical arrangement structure of Japanese Unexamined Patent Publication No. 2006-051581, it is easy to exchange or add an umbilical member, etc., to the system when necessary. However, liquid or dust may be introduced into the hollow portion through the openings of the wrist element and the base part of the forearm, whereby a servomotor within the hollow portion may be negatively affected by the liquid or dust. Therefore, it is difficult to use an industrial robot having such an umbilical arrangement structure in a waterproof application.
Further, the techniques in Japanese Unexamined Patent Publication (Kokai) No. 2005-342860 and Japanese Unexamined Patent Publication (Kokai) No. 2009-028875 are characterized by the configuration of the conduit through which the umbilical member is inserted. However, in both cases, the hollow portion is not waterproofed.